The Dark Horse singer joined the glitterati on Karl Lagerfeld's yacht for a boat party in New York on Monday night, wearing head-to-toe Chanel, naturally.

Even though her striped skirt looked like it was made from the same plastic as those reusable bags supermarkets force you to carry nowadays, it was pretty sophisticated when teamed with a collared blouse and black pumps.

We can just hear the crinkle noise it makes when Katy sits down!

The 30-year-old also had on a pair of pearl earrings and a nose ring, which was probably not Chanel, but you never know!